The transparency of zirconia is described by the index of the remaining transmittance after a certain amount of light passes through a certain thickness of zirconia.
For example, if the light of a flashlight shines on a stainless steel plate with a certain thickness, you cannot see the flashlight on the other end of the stainless steel plate, then the transmittance of this steel plate is 0%; If the glass is transparent enough, the intensity of the light you see through the glass is almost the same as what you see after removing the glass. , then the transmittance of that glass plate is close to 100%.
Initially, the transmittance of zirconia was more than 20%. With the continuous efforts of zirconia raw material manufacturers, it has 35%, 44%, 47%, 50% transmittance, and dental zirconia raw materials with a certain strength are also available. appear one after another.
Generally speaking, the light transmittance of zirconia blocks on the market and products with ordinary transmittance are about 30%-35% (1mm thick sample, 740nm wavelength), and the three-point bending strength is 1200-1400MPa;
For high transmittance products, the transmittance is about 40-45%, and the three-point bending strength is 1000-1200MPa; for ultra-high transmittance products, the light transmittance is about 48-50%, and the three-point bending strength is 600 -1000MPa. There is also a metallic zirconia that needs to be shaded for implant restoration. This zirconia needs to be extremely opaque, with a light transmittance of about 20% or less, and a strength of about 1000Mpa.
Aesthetically, we need zirconia with high transparency, close to the color of natural teeth, and sometimes extremely opaque zirconia for aesthetic purposes. The market demand is diverse, and raw material manufacturers and zirconia block manufacturers are also making unremitting efforts.
In order to make the zirconia restoration more beautiful and closer to the gradient color of the patient's natural teeth, most zirconium block manufacturers have also introduced multi-layered zirconia blocks (or gradient colors) to simulate the anatomy and histological structure of natural teeth. Even fluorescent zirconia blocks appear.
